Telephone signaling system



Oct. 23, 1928.

C. S. DEMAREST El' AL TELEPHONE SIGNALINQ sYsTsu Filed may 19. 192s 3.2.Sgm

A TTORNE Y Asignals over the telephone circuits.

Patented Octo 23, 1928.

...taire STATES PAT E Nfr or F11-CE..

CHARLESL s. nnlvreniiszr; or, ninefnwoon, vNava.inrisriv., Aim; owenromans c; p

BnooKLYn, NEW. YQRKS assienoas'ro inwinneni;v TELEPHQHE NQ TELEGRPHooivrrANY, A ooRroRATioii on NEW YORK. Y

TELEPHONE seNALrNs s'ifs'rnivi.

Application led May 19,

This invention relates to telephone signaling systems, andV moreparticularly to arrangements r'or transmitting supervisory signalsbetween central oiiice stations.

ln, the` operation of' a group o'l telephone circuits by improvedtraflic method@ anumber oi supervisory signals are required.` Facilitiesfor the transmission offtliese supe-rvisory signals are sometimes notavailable, as inthe case of radio speechchannels; anch-in the case. orivire circuits, they cannot always be obtained unless there aresacriiiced facilities i'or the transmission of lrorse telegraphFurthermore7 with the present standard facilities for signaling overvoice circuits, certain precautions must be taken in order to guardagainst interference with the signals bythe voice currents and' in orderto reduce the -i-nterference Jfrom other voice circuits and theinterference caused 'in= other voice circuits.

It is the object ofapplicants7 invention'to transmit supervisory`signals in cases in Which the facilities 'cannot loe obtained by Wiremeans, as in the' case 'of radio speech channels; and, in the case ofWire cir-cuits; to transmit such signalfsjivithout-any sacrilice oi"Morsetelegraph facilities andi Without any of the types of interferencementioned above.

Applicants accomplish this fobject by trans-l mitting all thesupervisory signals for-Ia.

group of voice circuits over a common radio channel between the centraloliice stations.

rflic arrangement described below and illustrated diagrainmatically inthel accompanying' drawing is one suitable for transmitting byapplicants means the signals'employed inthe so-called fring down77method otoperation, in which the central oiiice operators plug into andring over thecircuits also used for the subscribers" conversation. l

lNith reference to the accompanying drawing, station A is a teleplionecentral o?" ce station connected with a distantcentral oiice station Bby a plurality of'v-oice channels, Which-may be ordinary Wire circuits,carrier circuits7 or radio channels. yhesystem is shown equipped foroperation in citherdirect-ion,y that for the initiation of a call ateither station and the proper signaling` and supervision at bothstations. The apparatus at each station consists essentially of radiotransmittini7 means7 radio receiving 1926. [serial No. 110,249.

*means and the following in association with each` oi the voicechannels; means for lpro-r ducingradio signaling Acurrentl fortjansmission7 nicans'ior suitablytuning the rcceivin-gv means; the usualannunciator, and meansfor associating the signaling current producerandthe annunciator'with the rad-ioy transmitting and receiving apparatus7Vrespect'ively.A VFor-.each voice channel served and the receiver atv theotherv station beingl v correspondinglytuned by the circuit associatedwith that channel. Itl is to be understood that only the apparatusassociatedavith one voice channel is shown in full, the apparatuspeculiarly associated `withl 'the other channels being merely indicatedand; its con-` nection to the radio transmitting andreceiving apparatusshown. y i

rlhe details off the-'signaling' system ivillbe clearly understood?.from the following description of` the operation thereof'. s

If a subscriber directly vconnected With the cent1-al o iice station'AWishes to communicate WithY a, subscriber connected' With the distantcentral-office station Bytlie operatorv atV stati/'011A plfu'gstheftol-l cordinto jack J. Battery from the' sleeve of the toll cordoperates relay Cj The operator then' rings,

.the ringing current beingrrrapplied over the leads T land R' to relayD, which operates. The relay D, upon operation, in` turn operates relayE. Theoperation of relay E connects 'the oscillator' Of, Whichl'produceshigh frequency si-gnalingfcurrena through the'tunedcircuit Fassociatedwith the voice channel under consideration 'and through the commonampliiier G tothe radio transmitting antenna .of station A. At thedistantst'atiou B a-.ra'dio signal is received in the receivingVantenna, is changed"r in fre-f quenc'y (an oscillatorv` being associatedvWith the PF-reque'ncy changer), *andy 1s passedlooks through its`lovver Winding.V The locking circuitof the relay includes the lamp LQwhichr is" associatedY With the jack JA.

` through thecommon amplifier H, the .tuned i Therefore, when thelocking circuit of the relay is closed, this lamp lights. In response tothe operation of the lamp L, the operator at station B plugs the tollcord into the j ack J. Battery fromV the sleeve of the toll cordoperates relay C. Upon the operation of this relay the locking circuitofv relay N is broken, relay N is released, and lamp L is extinguished.

If'the operator at station A rei-ings, the ringing current over leads 'land R reoperates relay D, and a second radio signalv is transmitted tostation B in the mannei described above. Relay N at station B againresponds, but, since relay C remains operated, the lame L Will not lightagain, but relay P Will lie operated, the circuit to this relay beingVthrough the malte Contact` of relaypC. The operation of relay P connectsto the leads T and R the current sourceand ground indicated in thedrawing, and consequently ringing current is trans# mitted over theseleads to the toll cord previously inserted in the jack J. As is Wellunderstood in the art this ringing current operates an alternatingcurrent relay, which,

in turn, lights the supervisory lamp in the.

toll cord.` n

Only vso much of the toll cord circuitcateach station is shown asappears to be necessary to a full understanding ofr appli- ,cantsinvention.

' theleads T and R to relay D", which oper ates. rIfhe operation of thisrelay operates, in turn, relay E.' The operation of relay E connects theoscillator O, which produces high frequency signaling current, throughthe tuned circuit 15; and the common amplilier G to the radiotransmitting antenna of station B. At the distant station A, the radiosignal is received in the receiving antenna, is changed in frequency andis passed through a common amplifier H, the tuned circuit K, and therectifier M to the relay,V N. Relay N` operates and locks through itsupper Winding. The locking circuit includes the lamp L. associated `withthe jack J. Accordingly, when the locking circuit is completed,v thislamp lights, giving the signal to the operator at station A, Whoresponds by plugging the toll cord 'int-o jaclrJ. Battery from thesleeve of the tollfcord operates relay C, its operation breaking thelocking circuit `of relay N and extinguishing the lamp L. if

the operator at station B rerings, ringing current is again transmittedover the leads T. and R, and relay D is again operated.

rlhe re-operation of relay D results in the transmission of a secondradio signal to sta-` tion A, and relay N again responds. Since relay Cremains operated, lampr L Will vnot relight, but relay P vvill beoperated, the

circuit to this relay being completed at thev make contart ofrelay C.The operation of relay l) connects to the lea-ds T and R the currentsource and ground indicated in the drawing, and ringing current istransmitted over these leads to the toll cord previously r inserted linthe jack J. c Nhileapplicants invention has been described in onespecific embodiment which is deemed desirable, it is to be understoodthat it is capableof embodiment in many other and different` formsWithout a departure from the scope of the invention as defined in theappended claims.

TWhat is claimed is: l. In a telephone system,

connecting said stations, means at each station for transmittingradiosignals,means at each station for receiving radio signals, and ateach station in association Witheacli voice channel Ithe following:signal announcing means, means for producing signaling current peculiarin frequency to that station station, and automatic means for operatinglie'si'gnal announcing means at that station in response to radiosignals the other station.

2. In a telephonevsystem including ttvo tivo central otiice stations, aplurality of voice channels received fromA central oiice stations andavoizechannelV connecting said stations, means at each sta.- tion forgenerating and transn'ntting radio signals, means at each station forreceiving the radio signals transmitted from the yother station, anannunciator at each station, lautomatic means at each station,responsive t0- ringing cu 1rent introduced into thevoiceV channel atthat station, for operating the signal generating and. transmittingvmeans at that station, automatic means ateach station for operatingtheannunciator at that station in response Vto an initial radio sigllt) nalreceived from the other station, and automatic-means at each station forproducp ing ringing Vcurrent at thatstation in re spense to a subseqentradio signal received frein the other station.

In, a telephone system includingV tivo ycentral ofiice ystations and avoice channel connecting said stations, means at each station forgenerating andrtransmitting radiov signals,means at each station forreceivingV the radio signals transmitted from the other station, anannunciator at each station, automati'c means at each station,responsive to ringing current introduced into the voice channelat thatstation, for operating the signal generating; andftransmitting means atthat station, automatic means lat each station for operating theannunciator at that.

station in response to an initial radio signal received froin'the otherstation, automatic means at each station for producing ringingsubsequent radio signal received from the' other station. Y n n e'. lu'a telephone system including two central otice stations and' apluralityoflvoice channels connecting said stations, means at each station fortransmittingV radio signals, means at each station for receiving radiosignals, and ateach station in association with each voice channel thefollowing: means for fixing the frequency of the radio signalstransmittedfrom that station at a value peculiar tothat station and tothat voice channel,A means for tuning theV signal receiving means atthat station to the peculiar frequency Y of the radio signalstransmitted from the other station and corresponding to that voicechannel, an annunciator, automatic means, responsive to ringing currentintroduced'into that voice channel at that station, for operating thesignal transmitting means at that station, automatic means foroperatingvthe annunciator at that station in response to an initialradio signal, of the predetermined frequency, received from theotherstation, and automatic means for producing ringing Cur-Y rent atthat station inresponse to a suhsequent radio signal, of thepredetermined frequency, received from the other station.

5. ln a telephone systemrincluding two central office stations and aplurality of voice channels connecting said stations, means at eachstation for transmitting radio signals, means at each station forreceiving radio signals, and ateach station in association with eachvoice channel the following:

means for fixing the frequency of the radio signals transmitted fromthat station at a value peculiar to that station and to that voicechannel, meansA for tuning the signal receiving vmeans aty thatv stationto the peculiar frequency of ythe Vradio signals ltransmitted from theother station and corresponding to that voice channel, an annunciator,automatic means, responsive to ringing current introduced into thatvoice channel at that station,'for operating the signal transmittingmeans at that station7 automatic means for operating the annunciatorat:- that sta-tion in response to an'finitia-ll radio signal, of thepredetermined frequency, received from the other station,

automatic means for producing ringing cur-` rent at that station inresponsev to a 'suhseque-I'it-radioI signal', of the predeterminedfrequency, received from the other station, and' automatic means forpreventing the reopera-tion of the ann-unciator: at'that sta-tion inresponse to said subsequent radio signal received from the otherstation. f

In a telephone system ineIud-ingtWO- centraloilice stations and aplurality of voicechannels connecting'said stations, means at' ea'ch..station'for transmitting rad-io signals,

moan-s ateach station for receiving radio' an annuncia-tor, automaticmeans, responsiveA to ringing current introduced into that voicer`channel atr that station, for connecting saidl current producingmeans'tothe radio signal transmitting means Vat that station, auton matic meansfor operating the annunciator at that station in response to an initialradio signal, of the predetermined frequency, re ceived from the otherstation, and automatic means for producing ringing currentat thatstation in response to a subsequent radio signal, of the predeterminedfrequency, received from the other station. f Y

7. In a telephone system including two central oflice stations and apluralityl of voice channels connecting said stations, means at `eachstation for transmitting radio signals,

means at each station for. receiving radio signals, and atk each stationin .association with each voice channel the following: means for`producing signaling current kof a frequency peculiar to. that stationand/to'that voice channel, means for tuning the'signal receivingmeans atthat station to the peculiar frequency produced at the other station'andcorresponding to that voice chan nel, an annunciator, automatic means,responsive to ringingv current introduced into that voice channel atthat station, for connecting said current producing'means to the radiosignal transmitting means atthat station, automatic means foroperating/the annunciator atthat station in response to an initial radiosignal, of the'predetermined frequency, received from the otherstation,`

automatic means for producing ringing curquent radio signal, of thevpredetermined frequency, received from the other station, and` automaticmeans for preventing the re-operation of the annunciator at the stationin rerent at that station in response, to a subsesponse to saidsubsequent radio signal received from the other station. y

t 8. In a. telephone system, a sending station, a receiving station, avoice channel connecting said stations and including a. line circuit anda cord circuit, adapted to be interconnected, at each station and atransmitting medium, a signal annunciator and` a line source of ringingcurrent at the receiving stas tion, means at the sending station forgenerating and transmittingI radio signals, means at the receivingstation for receiving radio signals meansV at the sending station foroperating the singnal generating and transmitting means in response toringing current from the cord circuit, means at the receiving stationfor operating the signal annunciator in response to radiosignals onlyWhen the line and cord circuits at said station are disconnected,andmeans at said station for operating the line source of ringingcurrent in response to radio signals only When said circuits areinterconnected.

9. In a telephone system, including tvvo central oiiice stations and a.plurality of voice channels connecting said stations7 each of said voicechannels including a line circuit and a cord circuit, ladapted to beinterconnected, at each station and a transmitting medium, means ateacli station for transmitting radio signals, means at eachstation lforVannunciator, a line 'source of ringing` cur-4,

rent, means responsive to'iinging current from the cord circuit foroperating thefsigfl nal transmitting ineansat that station,ineans foroperating the signal-annunicator atltli'at station in response to radiosignals only when the line and cord circuits at that station aredisconnected, and ineansfor operatingtlie line source of ringing currentat that station Y y in response to radio signals only When said circuitsare interconnected In testimony whereof, We have signed our names tothis specification this 18th day of May, '1926. i V

CHARLES S. DEMAREST. OVEN H. LQYNES. c Y t

